In recent years, increases in degree of integration and scale of electronic devices have caused heat generation from and power consumption of electrical interconnections used frequently for connection between boards in the devices and between chips on the boards to become problems. To solve the problems, an optical interconnection technique has been developed which replaces these electrical interconnections with light-weight low-heat-generating flexible optical waveguides and optical fibers.
For such optical interconnections, the standardization of the shapes, dimensions, and testing methods of optical connectors used for coupling between boards and the like under JIS (Japanese Industrial Standards) has been promoted, and the forms of alignment and coupling between optical connectors have been standardized. Thus, the optical connectors have been easily connectable to other optical connectors of different types (see NPL 1, for example).
For example, as shown in FIG. 16, a first optical connector in which a PMT ferrule (a general-purpose ferrule for an optical waveguide) 2 is attached to an end portion (a terminus) of an optical waveguide 1 and a second optical connector in which an MT ferrule (a general-purpose ferrule for an optical fiber) 4 is attached to an end portion of a multi-core optical fiber 3 are easily connected (optically coupled) to each other, with the optical axes of the first and second optical connectors positioned using two guide pins 5 with high accuracy. In the present disclosure, an optical waveguide and an optical fiber are collectively referred to as a “light guide” in some cases.
A known example of the optical connector is obtained by assembling optical connector members configured as shown in FIG. 17 together (see PTL 1). The optical connector members are assembled in a manner to be described below. First, with the optical waveguide 1 inserted through a PMT boot portion 6, an end portion of the optical waveguide 1 having upper and lower surfaces coated with an adhesive agent is fitted in an optical waveguide fitting groove 8 formed in an upper surface of a PMT ferrule body portion 7. Then, positioning is effected so that a front end surface 1a of the optical waveguide 1 is uncovered at (flush with) a front end surface 7a of the PMT ferrule body portion 7. Next, the PMT boot portion 6 is pressed into an opening in a rear end surface 7b of the PMT ferrule body portion 7, and a PMT cover portion 9 is pressed from above. With this condition maintained, the adhesive agent is cured, so that all of the optical connector members are integrated together. If part of the adhesive agent juts as a burr out of the front end surface 7a of the PMT ferrule body portion 7 serving as an optical coupling surface or the front end surface 1a of the optical waveguide 1 is not clean, proper optical coupling is not achieved. In such a case, the front end surface 7a of the PMT ferrule body portion 7 is polished. In this manner, the optical connector is obtained.
Also known is an optical connector in which a lens array is provided on a front end surface of an optical waveguide to provide a light gathering capability without achieving optical coupling by bringing the front end surface of the optical waveguide into direct abutment with a front end surface of an optical fiber or the like (see PTL 2).